Antimicrobial Prenylated Xanthones and Anthraquinones from Barks and Fruits of Psorospermum adamauense (Engl)

One new prenylated xanthone derivative, named adamaxanthone (1) and one new prenylated anthraquinone derivative, adamaquinone (2) were isolated, respectively, from the methanol extract of the fruits and the stem bark of Psorospermum adamauense along with nine known compounds, including two xanthones [1,4,5,7-tetrahydroxyxanthone (3) and 1,2,3-trimethoxyxanthone (4)], two anthraquinones [2-isoprenylemodin (5) and (vismiaquinone (6)], one ferruginin [kengaquinone (7)], two anthrones [kenganthranol A (8) and 3-geranyloxyemodinanthrone (9)], one bianthrone [bianthrone A2b (10)], and one flavonoid [catechin (11)]. The structures of the new compounds were elucidated using spectroscopic methods and by comparison of their spectral data with those of the previously known analogues. The isolated compounds were evaluated for their antimicrobial activity against a wide range of drug-resistant pathogens and compound (3) was revealed to be the most active.